One of interleaved switching-mode power supplies of related art is disclosed in FIG. 1 of Patent Document 1. Regarding the interleaved switching-mode power supply of the related art, for example, each of two critical-mode boost-chopper converters includes a control circuit that controls on/off of a switch element provided between the other terminal of a transformer and a ground. The control circuit of the first critical-mode boost-chopper converter generates an on-timing of the switch element of the first critical-mode boost-chopper converter based on the voltage of a control coil of the first critical-mode boost-chopper converter. The control circuit of the second critical-mode boost-chopper converter generates an on-timing of the switch element of the second critical-mode boost-chopper converter at the timing at which the switch element of the first critical-mode boost-chopper converter turns off.
The interleaved switching-mode power supply disclosed in FIG. 1 of Patent Document 1 has the configuration such that FB terminals of the two critical-mode boost-chopper converters are commonly coupled and GND terminals thereof are commonly coupled, thereby achieving the interleaved switching-mode power supply that can be controlled by the extremely simple configuration.
In such the system having the above configuration that the FB terminals of the two critical-mode boost-chopper converters are commonly coupled and GND terminals thereof are commonly coupled, it is necessary to use the control circuits for the first and second critical-mode boost-chopper converters that have substantially approximate relationships between the voltage of the FB terminal (VFB) and the on-interval of the switch element Q31 (TON) as shown in FIG. 4 of Patent Document 1.